Python tutorial： python中文快速学习笔记 - 数字与字符串

3. python 数字与字符串

词汇：

plus +

subtract -

mulitply *

division /

divisor 除数

reminder 余数

power    ** 幂

equal  = 

fraction 小数部分

complex number  复数

decimal 十进制

parenthesis  圆括号

square parenthesis 方括号

brace  花括号

int integer 整数

float 浮点数

single quotes  ‘ ’

double quotes ” “

blackslash 、

raw string   r

triple-quotes ”“”   “”“

unicode  u

3.1 数字及运算

>>> 3 + 1
4
>>> 3 * (2 + 1)
9
>>> 7 / 2  # division
3
>>> 7 % 2
1          # reminder
>>> 7.0 /  2  # float division
3.5
>>> 7.0 //  2
3.0
>>> 2**10  # power
1024
>>> price = 10
>>> tax = price * 12 / 100
>>> print price, tax
10 1
>>> print price + tax
<pre name="code" class="python" style="font-size: 18px;">11

内部变量 “_" 会默认获得最后一个计算的值，被print函数引用的除外

>>> 2 + 3
5
>>> _
5
>>> a = 6
>>> a * 3
18
>>> _
18
>>> print a * 10
60
>>> _
18
>>>

3.2 字符

单引号与双引号用法：

>>> 'spam eggs'  # single quotes
'spam eggs'
>>> 'doesn\'t'  # use \' to escape the single quote...
"doesn't"
>>> "doesn't"  # ...or use double quotes instead
"doesn't"
>>> '"Yes," he said.'
'"Yes," he said.'
>>> "\"Yes,\" he said."
'"Yes," he said.'
>>> '"Isn\'t," she said.'
'"Isn\'t," she said.'

raw string， 用r字符可以屏蔽掉特殊字符

>>> print 'C:\some\name'  # here \n means newline!
C:\some
ame
>>> print r'C:\some\name'  # note the r before the quote
C:\some\name

triple-quotes 可以让一个字符串跨行

print """\
Usage: thingy [OPTIONS]
-h                        Display this usage message
-H hostname               Hostname to connect to
"""

字符串可以用加号来互相连接， 乘以数字实现重复次数

>>> 'a good' + ' day' + '!'*3
'a good day!!!'

字符串可以用分片的方式抽取部分或全部字符串。首个字符对应第0位。 word[<此位开始显示:<显示到此位以前>]

>>> word = 'agoodday'
>>> word[1:3]
'go'

>>> word[:3]
'ago'
>>> word[-2]
'a'
>>> word[-1]
'y'

len() 字符串的函数， 用来计算字符串长度

>>> len(word)
8

3.3. unicode 字符串

>>> current = u'￥'
>>> print current
￥
>>> current.encode('utf-8')
'\xef\xbf\xa5'
>>>